The invention pertains to the field of lawnmowers. More particularly, the invention pertains to lawnmowers of the riding type having both front and rear independent suspension.
The present invention is described with respect to its use on riding lawn mowers, particularly self-propelled machines fitted with rotating blades for cutting turf grasses. In the most favored typical design, the rider sits atop a three or four wheeled machine, while one or more blades rotate about a vertical axis within a mower deck mounted at the underside of the machine, to cut grasses as the machine moves across the surface being mowed.
In many typical riding mowers, the cutter deck is configured as either a ground-following deck or a floating deck. A ground-following deck typically rides on either two or four caster wheels and follows the contours of the ground. A floating deck is hung between the front and rear wheels and beneath the chassis by chains, links or other devices, being adapted to rise up when skids, wheels, rollers and the like attached to the underside of the deck make contact with the lawn surface. Generally, the intent for such deck suspension system is to avoid continuing contact with the earth surface. The distance of the cutter deck from the earth surface is determined by the elevation of the chassis. When the mower crosses an earth-surface rise which is relatively severe, that is, short in horizontal length compared to the wheel base of the mower and great in height compared to the pre-set elevation of the mower deck, the deck frequently makes contact with the earth surface. Then, it is intended that the deck rises or xe2x80x9cfloatsxe2x80x9d upwardly, so the rotary blades do not hit the earth surface. Such designs work well for many kinds of unevenness, but scalping for certain earth surfaces and mower movements is still a problem. Even if there is no scalping, a variation of the height of the cutter deck relative to the earth surface is not wanted, as it varies the height of the cut grass.
Many typical prior art mowers have the wheels rigidly attached to the chassis. Thus, unevenness in the earth surface imparts a lot of up and down chassis motion. Some prior art mowers employ center-pivoting axles which somewhat reduce the vertical motion of the chassis when one wheel encounters unevenness. The related applications describe a preferred transmission steerable mower which has rear drive wheels which are independently driven and spring suspended from the chassis, and which has free pivoting caster front wheels, mounted at the outer ends of a pivotable axle or subframe. The cutter deck is suspended between the front and rear wheels.
Mowers with improved spring suspension systems reduce the amount of chassis motion when one or both drive wheels of a mower encounter uneveness in the surface being mowed. Drive wheel traction is improved. However, depending on the particulars of any non-rigid suspension system, the chassis is enabled to roll relative to the earth surface, such as, for example, when the mower is sharply turning or when the mower is traversing a steep hillside. When a mower rolls, a floating cutter deck moves closer to the earth surface and there can be a tendency for scalping of the turf by the cutter deck. An improvement in one of the related applications connects the cutter deck with the rear wheels, thereby ensuring that the cutter deck moves relative to the wheels and ground instead of relative to the chassis of the mower.
Briefly stated, a lawn mower includes a front wheel suspension system as well as a rear wheel suspension system. The front wheel suspension system includes upper and lower suspension struts that are pivotably connected between a main frame of the lawn mower and a longitudinal suspension strut that is connected to a front wheel. A spring is connected between an extension of the upper suspension strut and a front transverse member of the main frame. The rear wheel suspension system includes upper and lower links that are pivotably connected between vertical struts that are connected between upper and lower frame members of the main frame and a motor mount. A spring is connected between a spring bracket extending from the upper frame member and either the motor mount or a motor mounted in the motor mount. In order to prevent scalping while turning, a floating cutter deck is suspended from the front and rear wheel suspension systems rather than from the main frame or chassis of the mower. An alternative embodiment includes a hinged pivoting subframe with springs between the main frame and the left and right halves of the subframe. In this alternative embodiment, the front of the cutter deck is suspended from the main frame while the rear of the cutter deck is suspended from the rear wheel suspension system.
According to an embodiment of the invention, a mower includes a main frame; first and second front wheels; and first and second front suspension systems connecting the first and second front wheels, respectively, to the main frame.